Localized surface modification for microfluidic applications

Abstract

Techniques for localized surface modification for microfluidic applications are provided. In one aspect, a method includes: contacting at least one portion of a surface with at least one tri(m)ethoxysilane-containing solution under conditions sufficient to form at least one silane monolayer having a given contact angle on the surface thereby modifying a flow rate over the surface. The silane monolayer can include a silane derivative selected from: trimethoxysilyl-propoxypolyethyleneoxide (TMS-PPEO), hexadecyl-triethoxysilane (HD-TES), tridecafluoro-1,1,2,2-tetrahydrooctyl)triethoxysilane (TDF-THO-TES), and combinations thereof. A device modified in accordance with the present techniques is also provided.

What is claimed is: 
     
       1. A method comprising:
 contacting at least one portion of a surface with at least one tri(m)ethoxysilane-containing solution under conditions sufficient to form at least one silane monolayer on the surface thus resulting in a modified surface having a given contact angle with a fluid flowing over the modified surface thereby modifying a flow rate of the fluid over the modified surface, 
 wherein the at least one silane monolayer comprises at least one first silane monolayer resulting in the modified surface having a first contact angle CA 1  with the fluid and at least one second silane monolayer resulting in the modified surface having a second contact angle CA 2  with the fluid, wherein CA 1  >CA 2 , and wherein the at least one second silane monolayer, which is coplanar with the at least one first silane monolayer, is formed on the surface in between two regions of the at least one first silane monolayer creating a fluidic channel on the surface. 
 
     
     
       2. The method of  claim 1 , wherein the at least one silane monolayer comprises a silane derivative selected from the group consisting of: trimethoxysilyl-propoxypolyethyleneoxide (TMS-PPEO), hexadecyl-triethoxysilane (HD-TES), tridecafluoro-1,1,2,2-tetrahydrooctyl triethoxysilane (TDF-THO-TES), and combinations thereof. 
     
     
       3. The method of  claim 1 , wherein the conditions comprise a reaction temperature and duration. 
     
     
       4. The method of  claim 3 , wherein the reaction temperature is from about 70° C. to about 130° C., and ranges therebetween. 
     
     
       5. The method of  claim 3 , wherein the reaction duration is from about 1 hour to about 4 hours, and ranges therebetween. 
     
     
       6. The method of  claim 3 , further comprising:
 varying at least one of the reaction temperature and the reaction duration to tune the given contact angle. 
 
     
     
       7. The method of  claim 3 , further comprising:
 locally heating only select areas of the at least one portion of the surface to the reaction temperature. 
 
     
     
       8. The method of  claim 7 , wherein the select areas of the at least one portion of the surface are locally heated using local heaters or focused infrared (IR) irradiation. 
     
     
       9. The method of  claim 1 , further comprising:
 forming a dam on the surface isolating the at least one portion of the surface such that the at least one tri(m)ethoxysilane-containing solution is contacted with only the at least one portion of the surface. 
 
     
     
       10. The method of  claim 1 , further comprising:
 forming hydroxyl groups on the at least one portion of the surface prior to performing the contacting step. 
 
     
     
       11. The method of  claim 1 , further comprising:
 selectively depositing the at least one tri(m)ethoxysilane-containing solution onto the at least one portion of the surface. 
 
     
     
       12. The method of  claim 1 , wherein the at least one first silane monolayer is formed on a first portion of the surface, and wherein the at least one second silane monolayer is formed on a second portion of the surface. 
     
     
       13. A method comprising:
 contacting at least one portion of a surface with a tri(m)ethoxysilane-containing solution; 
 exposing the at least one portion of the surface to ultraviolet (UV) radiation to form at least one silane monolayer on the surface thus resulting in a modified surface having a given contact angle with a fluid flowing over the modified surface thereby modifying a flow rate of the fluid over the modified surface, 
 wherein the at least one silane monolayer comprises a silane derivative selected from the group consisting of: TMS-PPEO, HD-TES, TDF-THO-TES, and combinations thereof, wherein the at least one silane monolayer comprises at least one first silane monolayer resulting in the modified surface having a first contact angle CA 1  with the fluid and at least one second silane monolayer resulting in the modified surface having a second contact angle CA 2  with the fluid, wherein CA 1  >CA 2 , and wherein the at least one second silane monolayer, which is coplanar with the at least one first silane monolayer, is formed on the surface in between two regions of the at least one first silane monolayer creating a fluidic channel on the surface. 
 
     
     
       14. A device, comprising:
 at least one silane monolayer on at least one portion of at least one surface of a material thus resulting in a modified surface having a given contact angle with a fluid flowing over the modified surface that modifies a flow rate of the fluid over the modified surface, 
 wherein the at least one silane monolayer comprises a silane derivative selected from the group consisting of: TMS-PPEO, HD-TES, TDF-THO-TES, and combinations thereof, and wherein the at least one silane monolayer comprises at least one first silane monolayer resulting in the modified surface having a first contact angle CA 1  with the fluid and at least one second silane monolayer resulting in the modified surface having a second contact angle CA 2  with the fluid, wherein CA 1  >CA 2 , wherein the at least one second silane monolayer is formed on the surface in between two regions of the first silane monolayer creating a fluidic channel on the surface, wherein the at least one surface comprises a first surface and a second surface, wherein the at least one silane monolayer comprises dots disposed on both the first surface and the second surface, and wherein the first surface and the second surface are facing one another such that the dots are aligned into columns. 
 
     
     
       15. The device of  claim 14 , wherein the material comprises polyethylene terephthalate (PET).